Banquo and Macbeth can't really trust their eyes when they encounter the witches... "You should be women, and yet your beards forbid me to interpret that you are so." Macbeth also says he doesn't know if he imagines them or not since they just melt into the wind.

Again, Lady Macbeth tells her husband to "look like the innocent flower but be the serpent under it" when it comes time to kill Duncan. Their house appears warm and inviting, but they intend to kill him and they succeed.

Lady Macbeth appears to be a tough and callous woman--immune to all guilt and feeling, but we see her fall apart after Duncan's murder. She sleepwalks and is apparently not at all what she first seemed.

Of course, there are also the witches' prophecies. Macbeth doesn't realize the prophecies can mean anything other than how he interprets them. Of course, Macduff was born by c-section, so he was not technically born of woman. The armies advance up the hill from Birnam Wood with tree branches before them which makes it appear the wood is walking up the hill.

The theme of appearance versus reality is central to Macbeth. It pertains to Macbeth himself as he is first introduced as a nobleman, a fearless warrior who renders worthy service to his king – yet this same man is then revealed to have murderous thoughts in his heart, capable of plotting against his king and usurping the throne. On the outside, he presents an impeccable face to the world, so that no-one suspects, but when alone, or meeting privately with his wife – who actively encourages him in his murderous ambitions – we see the reality behind his public façade. Lady Macbeth counsels him to ‘look like the innocent flower but be the serpent under it’(I.v.62-63) when the time comes to kill Duncan, and, at first, he does this rather too well. Similarly, his castle presents a deceptively positive aspect to Duncan when he goes there at Macbeth’s invitation ‘ This castle hath a pleasant seat’(I.vi.1) – he has no inklings at all, seemingly, of the evil that awaits him inside.

The whole world of the play is profoundly unsettled with the murder of Duncan, which is presented not just as a foul but also wholly unnatural event, coming as it does at the hands of his kinsman and when he has done nothing to deserve such a fate. But even before this, and indeed in the very first scene of the play, a note of equivocation, of things being not as they seem, is introduced along with the witches. Among their first words are: ‘Fair is foul, and foul is fair’ (I.i.10) which strikes the note of ambivalence; and significantly, Macbeth’s first line echoes this: ‘So fair and foul a day I have not seen’.(I.iii.38). The witches introduce a supernatural element to the play which has a certain de-stabilizing effect, leading to the questioning of what is actually real, as opposed to mere appearances, imaginings, or delusions. However, the witches’ prediction of Macbeth’s kingship strikes a real enough note with him; it corresponds to his secret ambitions, and helps to propel him forward into the main tragic action of the play.

Duncan also says he can't find the mind's construction in the face, meaning he can't tell what people are truly like from what he sees on the outside.

In contrast to their father's inability to see the potential for danger beneath the surface, Malcolm and Donalbain say that where they are there are "daggers in men's smiles"--meaning, that they see smiles on the outside but they know that danger is beneath the apparently friendly appearance.

Also, Duncan says, "This castle hath a pleasant seat" upon arriving at Macbeth's castle, and, of course, as pleasant and restful as the castle looks on the outside, it is anything but that on the inside.

\"The terror the tragedy inspires is due to the abyss that lies between the inner natures of Macbeth and Lady Macbeth, and the murder which they perpetrate\" J.J. Chapman, \"A Glance toward Shakespeare\"
The disparity between M\'s and LM\'s words and actions; After killing Duncan M overdecorates (II.iii.4-13), the banquet scene (III.iv) in which M’s words belie his knowledge of Banquo\'s death. Or their actions and understandings: a character able to express such convincing horror before Duncan\'s murder would likely be incapable of committing the crime.
Equivocation itself. Equivocation is very relevant to the context of the play. You can use the Porter scene, all the witch’s prophesies and the witches themselves (beards but women, call their \"masters\" to them as servants etc).
The disparity between M\'s perception of reality and ...well... everyone else’s. Is it supernatural or M\'s guiltridden hallucinations?
The larger theme of inverted natural order. It is often considered that as M hides from his guilt in false hospitality his inner nature, once \"full of the milk of human kindness\" and now tormented, is embodied in the developing inhospitality and degradation of the natural world, (IV.iii & II.iv). The natural world appears foul but is fair (warning people), M\'s artifice appears fair but is really foul (hiding his murderous intent)

Another example to add is when Lady Macbeth plans out the murder for King Duncan. She tells Macbeth to hide their true intensions.

Lady Macbeth: "Only look up clear;

To alter favour ever us to fear."

Meaning raise your eyes and look confident. A change in the way one looks reveals fear and further arouses suspicion.

Macbeth as well tells himself: "False face must hide what the false heart doth know."

Also when Macbeth and Banquo arrive and meet the witches for the first time, Macbeth says: "So foul and fair a day I have not seen."

When Macbeth is told the 3 prophecies he will possess by the witches, he is unsure. Banquo says: "Good sir, why do you start, and seem to fear things that do sound so fair?" Meaning why do you fear of these great titles when they sound so good.

Little do they know, in order to get the third title, king of Scotland, Macbeth goes through countless dangerous actions and is soon lead by his downfall.

When Malcolm and Donalbain flee the country after their fathers death, suspicion is put on them for the murder.

When Macduff leaves to England to seek help from Malcolm, Malcolm is unsure of Macduff's loyalty. Therefore he tests Macduff, and in the end Malcolm learns that Macduff truly is loyal and wants what is best for his country.

Also the apparition of no man born of woman can harm Macbeth. Macbeth is convinced that no one can harm him since every human being is born of a woman. But Macduff was not naturaly born of a woman. Either caesarian or premature delivery occured therefore he ended the life of Macbeth.

At the beginning of the play, when Macbeth and Banquo meet the witches, Banquo says that Macbeth "seems rapt withal" upon hearing the prophecy. He appeared taken aback by the prophecy that stated that he shall become king. He seemed to be very innocent as he looked surprised. However, in his head he thought of "murder" which was still "fantastical". In reality, he was thinking about murdering King Duncan to achieve kingship.